Benthyc Insect Larvae of Small Rivers in Central Russia (Synecological Aspects)

Abstract

Many small rivers flow in the central and northern parts of the Meshora Lowland. Their peculiarity is bog and snow water supply, high anthropogenic load and various overgrowing of the banks. The bottom ecosystems of these rivers include the larval stages of various insect species. The most common are representatives of the orders Diptera, Megaloptera, Odonata, Ephemeroptera, Trichoptera, Hemiptera. The study of benthic communities showed their significant difference in insect representation and biodiversity. The communities richest in species are peculiar to rivers and riverbed sections where the lowest ratio of dissolved organic matter to suspended matter was observed. At the same time, such communities are found not along the entire length of the river, but in spots. The collected data on various sections of the four rivers represent data on the synecology of insects with rheophilic freshwater larval stages, which make it possible to consider the benthic ecosystems of small Meshora rivers as the interaction of species and their place in detrital food webs, as well as their relationship with the areas of growth of aquatic macrophytes. The investigated bottom lotic ecosystems, including insects, can be described using the patch dynamics concept, but not the river continuum concept. This is apparently due to three factors: 1) Binding to thickets of macrophytes of food webs. 2) Separation of environments in the ontogeny of insects. The larvae develop in water, and the adults live in the ground-air environment, where the reproduction process takes place. Oviposition in water takes place in convenient places with characteristic vegetation. 3) There is an annual restoration of ecosystems from winter shelters or refugium. That allows insects to survive the winter freezing of the river, the lack of dissolved oxygen.